1. Field of the Invention
This invention relates to a rotor for hydrogen-cooled rotary electric machines wherein the rotor is cooled by hydrogen gas.
2. Description of the Prior Art
In rotary electric machines such as a hydrogen-cooled rotary electric machine, the following limitations are generally placed on the provision of passages for the gas for cooling the windings at the end of the rotor. A retaining ring for holding the windings in a predetermined position develops stress of high magnitude and it is not desirable to form gas flow passages in the retaining ring. This makes it inevitable to permit the gas to be introduced into and discharged from the windings through an annular surface disposed outside the end surface of the retaining ring and restricted by the rotor shaft. Moreover, the area that can be used for forming the gas inlet and outlet passages is further restricted and becomes essentially smaller than the area of the annular surface because of the fact that laminated windings occupy the major part of the zone between the retaining ring and rotor shaft and a center ring for axially supporting the laminated windings is located beneath the retaining ring. It has hitherto been one of the most important problems in the technology of cooling the windings at the end of the rotor how to provide inlet and outlet ports for the cooling gas under these circumstances.
Proposals have hitherto been made, as disclosed in Japanese Patent Publication No. 17725/78, to form grooves in the rotor shaft to increase the area of the gas inlet port for introducing gas into a gas inlet chamber, and to divide a gas outlet chamber near the polar axis into a first zone near the center ring and a second zone away therefrom, with two separate fan-like ventilating means each communicating with one of the two zones of the outlet chamber for release of the gas to the outside.